There are several ways for a handheld device such as a mobile phone or a tablet computer to determine its location. Conventional techniques include the use of a satellite-based positioning system such as GPS (Global Positioning System), or triangulation based on alteration in signals communicated between the mobile device and a plurality of base stations of a cellular network.
Various approaches have been proposed for indoor positioning systems including radio frequency (RF) based approaches, which are prone to have errors of tens of meters and they typically estimate two-dimensional position. Optical based solutions were introduced to address such challenges. However, the optical based systems were either not comprehensive or do not calculate positions accurately. U.S. Pat. Nos. 8,248,467, 8,334,901, 8,957,951 and 8,436,896 discloses optical indoor positioning systems using CMOS camera and Wi-Fi technology, which may be implemented on smartphones. The proposed positioning techniques include modulation and demodulation of unique codes generated by LED transmitters.
Firstly, using a CMOS camera to estimate the position is both expensive and challenging to be implemented on ordinary smartphones. Secondly, their accuracy is in the order of several decimeters, which is not appropriate for accurate indoor positioning applications. Further, some other optical techniques for indoor positioning estimate two dimensional positioning with two or more reference points. These systems have a large error exposure. For two-dimensional positioning, image sensor is expected to be horizontal and to have a pre-determined inclination. Therefore, there is a need in the art for a solution to the aforementioned problems.